Distributed wireless sensor networks consisting of several single sensors offer important benefits for a multitude of applications including battlefield surveillance, situation awareness and monitoring, urban warfare, homeland security and border control. Distributed wireless sensor networks can be used to capture acoustic signatures of a wide variety of sources including ground and airborne vehicles as well as transient events such as gunshots. Among the benefits of distributed wireless sensor networks are: simplicity and ease of deployment, stealthy operation in urban areas, large coverage area, good spatial resolution for separating multiple closely spaced sources, low hardware complexity and hence low costs, and flexibility in configuring different dynamic sensor array configurations.
Reducing the rate of data transmission from each sensor node to the base station not only reduces the cost and power consumption of each sensor node but also the complexity and cost of the base station. More importantly, it allows deploying a large number of sensor nodes to cover a large area without exceeding the bandwidth limitation of the wireless communication system. For example, in a system that uses zigbee-based communication protocols with sensor nodes based on the IEEE 802.15.4 standard, the data rate or bandwidth is 250 kilo bits per second (kbps) per channel. If each sensor node transmits 25 kbps, only 10 sensor nodes can communicate simultaneously to a base station. If each sensor node transmits 2 kbps, 125 sensor nodes can communicate simultaneously to a base station.
A system with sensor-level detection, feature extraction and data compression for low bit rate transmission of essential target attributes to the base station can significantly reduce the data rate relative to prior known systems. In moderately large sensor networks with sensor nodes that use communication protocols such as zigbee-based communication protocols that use the, data rates of less than 2 kbps per node are needed to meet the bandwidth limitations, while guaranteeing the usefulness of the data for accurately locating moving sources. Such a system can make practical the widespread use of low cost distributed wireless sensor nodes in many applications.
U.S. Pat. No. 7,005,981 to Wade discloses a system and method with sensor systems or nodes with the steps of pre-processing collected data, and applying a matched extraction/compression scheme to the pre-processed data. U.S. Patent Application Publication No. 2008/0069334 to Denby et al. discloses a system and method with a central server and agents with the steps of applying a statistical test to measurement data, and based on the results of the statistical test, determining whether an update needs to be sent from the agent to the server.